Guide tool for guiding downhole tools through wellbore restrictions

ABSTRACT

A guide tool for mounting onto a downhole tool for use in a wellbore penetrating subsurface formations is provided. The guide tool has a bull nose. The bull nose has a first section with an end for sealing against and engaging a lower end of the downhole tool and a second section axially deflectably coupled to the first section.

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority is claimed from U.S. Provisional Application No. 61/012,479, filed on Dec. 10, 2007.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to well interventions. More specifically, the invention relates to apparatus and method for guiding a downhole tool through a wellbore having wellbore restrictions.

2. Background Art

In the extraction of oil and gas from underground reservoirs, it is frequently necessary to insert a downhole tool or an assembly of such tools, e.g., a tool “string”, into a wellbore drilled through the reservoir. It can be difficult to push tool strings, examples of which include well completion strings, workover strings, and logging tool systems to the full depth of the wellbore due to restrictions in the wellbore. Examples of such restrictions include ledges and washouts created during the drilling of the wellbore, during well stimulation, during injection of fluids into the reservoir from the Earth's surface, or while producing fluids from the underground reservoir to the surface. Ledges and washouts may also be created as a result of collapse of the formation in which the wellbore is drilled, where the flow of fluids from within the wellbore is insufficient to move debris from the collapsed formation to the Earth's surface.

When inserting a relatively stiff (“stiff” being defined in terms of bending moment) tool string, e.g., a tubular string or a stiff well logging tool string, into a wellbore, the lower end of the stiff tool string can be prevented from going further into the wellbore if it lands against a washout or ledge formed as explained above. A semi-stiff, spoolable rod, such as described in International Application Publication No. WO 2006/003477, and used to provide services under the service mark ZIPLOG, which is service mark of the assignee of the present invention, may face the same challenge as the stiff tool string when traversing a wellbore with such restrictions. Another challenge related to such spoolable rods is that the well equipment operator cannot visually or otherwise determine if the lower end of the rod is moving or not. Failure to determine such movement while the surface end of the rod is being inserted into the wellbore can cause the equipment operator to continue pushing the rod into the wellbore against a stopped lower end of the rod, causing damage to or failure of the rod.

SUMMARY

In one aspect, a guide tool for mounting onto a downhole tool for use in a wellbore penetrating subsurface formations is provided. The guide tool has a bull nose. The bull nose has a first section with an end for sealing against and engaging a lower end of the downhole tool and a second section axially deflectably coupled to the first section.

In another aspect, an apparatus for use in a wellbore penetrating subsurface formations is provided. The apparatus comprises a downhole tool and a guide tool having a bull nose. The bull nose has a first section with an end that seals against and engages a lower end of the downhole tool and a second section axially deflectably coupled to the first section.

Other features and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, described below, illustrate typical examples of the invention and are not to be considered limiting of the scope of the invention, for the invention may admit to other equally effective examples. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

FIG. 1 shows a wellbore penetrating subsurface formations and an apparatus according to the present invention suspended in the wellbore.

FIG. 2 is a diagram of a portion of the apparatus of FIG. 1 illustrating a guide tool attached to a lower end of a downhole tool.

FIG. 3 shows the downhole tool and guide tool in an open hole section of a wellbore in a stopped position.

FIG. 4 shows the hole finder of the guide tool oriented outwardly in order to allow the downhole tool to continue along the wellbore.

FIG. 5 shows the downhole tool hung up in a restriction in the wellbore.

FIG. 6 shows the hole finder back in the neutral position, which allows the downhole tool to continue along the wellbore.

DETAILED DESCRIPTION

The invention will now be described in detail with reference to a few examples, as illustrated in the accompanying drawings. In describing the examples, numerous specific details may be set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without some or all of these specific details. In other instances, well-known features and/or processes may not be described in detail so as not to unnecessarily obscure the invention and because they would be within the ambit of one of skill in the art. In addition, like or identical reference numerals may be used to identify common or similar elements.

FIG. 1 shows a wellbore 100 drilled through subsurface formations 102, 104. Subsurface formation 104 may be a hydrocarbon producing formation. The wellbore 100 typically starts with a vertical portion 106, which can extend anywhere from hundreds to thousands of meters, and gradually or otherwise curves, for example, into a horizontal portion 108, which can extend for lengths up to several thousand meters. This particular wellbore configuration is meant to serve as an example of possible configurations of a wellbore that may be used with the invention and is not intended to limit the scope of the invention. A pipe or casing 110 extends from the surface 112 to a selected depth in the wellbore 100 and is cemented in place in the wellbore 100. A wellhead 114 is positioned at the surface 116, above the wellbore 100. The wellhead 114 includes various valves to regulate flow of fluids from within the wellbore 100, as will be familiar to those skilled in the art. The wellhead 114 also enables access into the wellbore 100 for drilling and well intervention, for example.

In the example illustrated in FIG. 1, a wellbore apparatus, generally identified at 118, extends from the wellhead 114 into the wellbore 100. The wellbore apparatus 118 includes a downhole tool 120. In some examples, the downhole tool 120 may be a semi-stiff tool, such as a semi-stiff, spoolable rod, as described in, for example, International Publication No. WO 2006/003477, and as stated in the Background section herein is used to provide services under the service mark ZIPLOG by the assignee of the present invention. As described in the '477 publication, the spoolable rod includes one or more optical fibers encased in a thin metal barrier layer, which in turn is encased in a composite layer. The downhole tool 120 may be coupled to a surface system 122, which may include, for example, a recording unit, a communications unit, and/or a measurement unit (none of which is shown separately). In other examples, the downhole tool 120 may be a stiff tool string made of wellbore tubulars such as production tubing or drill pipe. The downhole tool 120 may be used for work or intervention in the wellbore 110. According to the present invention, the wellbore apparatus 118 includes a guide tool 124 attached to the lower end of the downhole tool 120. As will be explained below, the guide tool 124 guides the lower end of the downhole tool 120 through unexpected restrictions in the wellbore 100.

FIG. 2 is a simplified diagram showing the guide tool 124 and the features that enable the guide tool 124 to guide the downhole tool 120 through unexpected restrictions in a wellbore. In the diagram shown in FIG. 2, the guide tool 124 includes a bull nose 126 having an upper end 128 that is attached to the downhole tool 120 and a lower end 130 that is free. The shape of the lower end 130 is generally rounded and configured to guide the bull nose 126 through the wellbore and away from restrictions in the wellbore, such as, for example, liner hanger top, ledges, and/or washouts. The shape of the upper end 128 may be similar to that of the lower end 130 and may serve the same purpose as described above when the downhole tool 120 is being pulled out of the wellbore. The bull nose 126 with the rounded upper end 128 and lower end 130 has a capsule shape in a neutral position. The upper end 128 of the bull nose 126 may be attached to the downhole tool 120 via any suitable mechanical gripping arrangement, indicated generally at 135. In some examples, the mechanical gripping arrangement 135 may be similar to what is used to seal hydraulic tubing in a wellbore, as will be familiar to those skilled in the art. In some examples, the upper end 128 of the bull nose 126 sealingly engages the lower end 125 of the downhole tool 120, thereby providing a pressure seal barrier that prevents wellbore fluids from entering into an area between the bull nose 126 and downhole tool 120 and the interior of the downhole tool 120. The upper end 128 may sealingly engage the lower end 125 of the downhole tool 120 via the mechanical gripping arrangement 135.

The guide tool 124 may include one or more sensors, shown generally at 132. In some examples, sensor 132 a may be a vibration sensor for measuring vibration of the downhole tool 120. Vibration data from the vibration sensor 132 a may be sent to the surface and can be interpreted to determine if the downhole tool 120 is moving in the wellbore or not, or to determine the depth of the downhole tool 120 in the wellbore. If the readout of the vibration sensor 132 a at the surface indicates no vibration, the operator may conclude that the lower end of the downhole tool 120 is not moving and may stop insertion or retraction of the downhole tool 120 into or from the wellbore before physical damage to the downhole tool 120 or wellbore takes place. In other examples, sensor 132 b may be a temperature sensor for measuring differential temperature in the wellbore. Such differential temperature may be correlated to the depth of the downhole tool 120 in the wellbore. In other examples, sensor 132 c may be a pressure sensor for sensing pressure external to the guide tool 124 or downhole tool 120.

Sensor(s) 132 as described above may be fiber-optic or electrical. In some examples, the guide tool 124 may include a fiber splice, shown generally at 133, for making connections between an optical fiber(s) in the guide tool 124 and an optical fiber(s) in the downhole tool 120. In other examples, the guide tool 124 may include an electrical connector (not shown separately) for making electrical connections between electrical components in the guide tool 124 and electrical components in the downhole tool 120, e.g., where the sensor(s) 132 are electrical. The seal provided at the upper end 128 of the bull nose 126, as explained above, may function to prevent unwanted fluid from entering into an area where the fiber optic and/or electrical connections are made.

The bull nose 126 has an upper section 134 including the upper end 128 and a lower section 136 including the lower end 130. The lower section 136 may be coupled to the upper section 134 via an indexing system, identified generally at 138. The indexing system 138 provides indexed movement or deflection of the longitudinal axis of the lower section 136 with respect to the longitudinal axis of the upper section 134. The indexing system 138 can deflect the lower section 136 relative to the upper section 134 through a set of preset angles, e.g., 0°, 45°, 90°, 120°, without decoupling the lower section 136 from the upper section 134. Deflection is enabled by rotation about the connection area, generally indicated at 139, between the upper section 134 and the lower section 136. The indexing system 138 may be, for example, mechanically-activated, pressure-activated, or electrically-activated. In some examples, a mechanically-activated indexing system 138 may be a spring-loaded indexing system that can be activated by adjustment of applied axial load. Such indexing may take the form of a set of J-slots (not shown) such as shown in U.S. Pat. No. 5,433,276 issued to Martain et al. The lower section 136 functions as a “hole finder” that will ensure that the bull nose 126 is oriented toward the continued wellbore in case the bull nose 126 is lodged against a restriction in the wellbore. A restriction in the wellbore is essentially any structure or feature that can stop the downhole tool 120 from progressing along the wellbore.

FIG. 3 shows the guide tool 124 and attached downhole tool 120 in an open hole section 142 of the wellbore 100. This example of the open hole section 142 includes a featured called a “washout” 144. In the example of FIG. 3, the downhole tool 120 is stopped from moving along the wellbore 100 by the washout 144. The well equipment operator at the surface may detect that the downhole tool 120 is no longer moving, for example, by receiving vibration data from the guide tool 124 and interpreting the vibration data. When it is determined that the downhole tool 120 is no longer moving, the operator can take actions to activate the hole finder 136. The hole finder 136 in the present example can be activated by controlling axial load on the downhole tool 120 from the surface. In some examples, the operator can cause the downhole tool 120 to move upwardly by removing axial load from the downhole tool 120. Removing axial load from the downhole tool 120 can cause the indexing system (138 in FIG. 2) to orient the hole finder 136 to an outward angle with respect to the longitudinal axis of the downhole tool 120, as shown in FIG. 4. In other examples, the operator can increase fluid pressure in the interior of the downhole tool 120 to cause the indexing system 138 to orient the hole finder 136 to an outward angle as described above. With the hole finder 136 oriented outwardly, the operator can move the downhole tool 120 downwardly (i.e., along the wellbore) once again, whereby the hole finder 136 overcomes the washout 144.

Referring to FIG. 5, orientation of the hole finder 136 after the activation described above may be such that the guide tool 124 becomes lodged in a later restriction 146 (such as a reduced-diameter section) in the wellbore 100, thereby preventing the downhole tool 120 from advancing along the wellbore 100. Again, the operator may determine that the downhole tool 120 is no longer moving by, for example, interpreting vibration data sent to the surface from sensors in the guide tool 124. In some examples, the operator may release the guide tool 124 by moving the downhole tool 120 upwardly as described above, wherein removal of axial load from the downhole tool 120 causes the hole finder 136 to move to the previous angle, which in FIG. 6 is the centered or neutral position where the hole finder 136 is aligned axially with the downhole tool 120. In other examples, the operator may cause the hole finder 136 to return to the previous angle (or centered/neutral position) by releasing pressure from the interior of the downhole tool 120. Once the hole finder 136 is reoriented, the operator can move the downhole tool 120 along the wellbore once again. If the downhole tool 120 hangs up once again in the wellbore 100, the hole finder 136 can be activated as described above to orient the hole finder 136 to a next outward angle, e.g., 450 from the previous angle. Activation of the hole finder 136 can be repeated as necessary to engage one or more of a number of different angle settings, for example, 0°, 45°, 90°, and 135° (where 0° may represent the neutral/centered position).

A guide tool according to the various aspects of the invention may provide a wellbore equipment operator to avoid tool damage, and to continue operations in a wellbore having obstructions with minimum delay.

While the invention has been described with respect to a limited number of examples, those skilled in the art, having benefit of this disclosure, will appreciate that other examples can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims. 

1. A guide tool for use in a wellbore penetrating subsurface formations, the guide tool having a bull nose, said bull nose having a first section with an end for sealing against and engaging a lower end of a downhole tool and a second section coupled to the first section such that an axis of the second section is deflectable to an axis of the first section.
 2. The guide tool of claim 1, wherein the second section is coupled to the first section by an indexing system that provides indexed deflection.
 3. The guide tool of claim 2, wherein the indexing system is mechanically-activated.
 4. The guide tool of claim 2, wherein the indexing system is pressure-activated.
 5. The guide tool of claim 1, further comprising a pressure sensor disposed in the bull nose.
 6. The guide tool of claim 1, further comprising a vibration sensor disposed in the bull nose.
 7. The guide tool of claim 1, further comprising a temperature sensor disposed in the bull nose.
 8. The guide tool of claim 1, further comprising a fiber splice coupled to the bull nose for making fiber connections.
 9. The guide tool of claim 1, wherein the bull nose has a capsule shape when in a neutral position.
 10. An apparatus for use in a wellbore penetrating subsurface formations, the apparatus comprising: a downhole tool; and
 11. a guide tool having a bull nose, said bull nose having a first section with an end that seals against and engages a lower end of the downhole tool and a second section coupled to the first section such that an axis of the second section is deflectable relative to an axis of the first section.
 12. The apparatus of claim 10, wherein the downhole tool comprises a spoolable rod.
 13. The apparatus of claim 10, wherein the downhole tool comprises one or more wellbore tubulars.
 14. The apparatus of claim 10, wherein the second section is coupled to the first section by an indexing system that provides indexed deflection.
 15. The apparatus of claim 13, wherein the indexing system is mechanically-activatable.
 16. The apparatus of claim 14, wherein the indexing system is activatable from a remote location by adjusting axial load on the downhole tool.
 17. The apparatus of claim 13, wherein the indexing system is pressure-activated.
 18. The apparatus of claim 16, wherein the indexing system is activatable from a remote location by adjusting pressure in the downhole tool.
 19. The apparatus of claim 10, further comprising a pressure sensor disposed in the bull nose.
 20. The apparatus of claim 10, further comprising a vibration sensor disposed in the bull nose.
 21. The apparatus of claim 10, further comprising a temperature sensor disposed in the bull nose. 